Usually Googlebots follow the robots.txt. If you didn't check already, maybe have a quick look if the IP addresses actually belong to google and not someone else.
Here's something you can use to block that s#!t until you get it sorted out.
If you add this to the top of your browse.php page it should stop the browse page from loading and restrict access to 'anyone' trying to go through your proxy with a googlebot or yandex useragent.
$ua = $_SERVER['HTTP_USER_AGENT'];
$detect = array('googlebot','yandex');
foreach($detect as $d)
if(stripos($ua,$d) !== false)
exit("<strong>$d</strong> detected - No proxy for you !");
You could also send them to the default Glype banned page:
or redirect them to another page with a message if you'd prefer to do something else to/with them.
header('HTTP/1.1 403 Forbidden', true, 403);
If you use it, let me know if you have any problems.
I added a little more info in this guide on How to block bots from accessing pages through your proxy .